1. Field of the Invention
The present invention relates to a lens barrel equipped with a rotation amount detecting encoder such as a pulse encoder for detecting an amount of shift of a focusing lens group, etc., and an assembling method thereof.
2. Related Background Art
Conventionally, in this type of lens barrel, the adjustment of an encoder is performed with a cam ring, a lens barrel and the other peripheral accessories incorporated in a fixed cylinder, so that the rotation angle of the encoder formed integrally on the cam ring is limited to a certain angle (the rotation angle of the cam ring).
Therefore, in the conventional lens barrel, the duty adjustment of pulses of the encoder is performed while reversing the cam ring by means of a limiting member. Therefore, means or a tool for moving the cam ring is required to have a reverse function, which causes the means or the tool to be complex and expensive.
Also, as the cam ring is made to rotate at higher speed, the time for the duty adjustment during rotation of the cam ring in one direction is shortened, whereby the adjustment becomes difficult.
Further, when the readjustment of the encoder is required due to an accident after the completion of assembly of the lens barrel, it is necessary to disassemble the lens barrel until the encoder section is exposed, so the repair is troublesome.